In video system applications, random noise present in video signals, such as NTSC or PAL signals, for example, may result in images that are less than visually pleasing to the viewer. Noise may also be present in digital video signals. Noise in video signals may adversely affect encoding of the video. To address this problem, noise reduction (NR) operations may be utilized to remove or mitigate the noise present. Traditional NR operations may use either infinite impulse response (IIR) filtering based methods or finite impulse response (FIR) filtering based methods. IIR filtering may be utilized to significantly attenuate high frequency noise. However, IIR filtering may result in visual artifacts such as motion trails, jittering, and/or wobbling at places where there is object motion when the amount of filtering is not sufficiently conservative. In some instances, setting the IIR filtering conservatively may mitigate the noise removing capability even for places where there is little or no motion, such as a static area in video. As a result, there may be many instances where objectionable noise artifacts remain in the video signal.
Another traditional NR operation may be FIR filtering based methods. FIR filtering may not be subject to artifacts such as motion trail, motion blurring, jittering and/or wobbling, for example, as much as IIR-based filtering may be. FIR filtering may provide acceptable perceptual quality for moving areas to most viewers. However, in a practical NR system, which may not be able to employ a large number of video images to perform FIR filtering as a result of the cost of storage, the system's noise reducing capability may be very limited in those areas where there is little or no motion.
In order to improve the NR effectiveness it may be necessary to achieve both significant NR in areas of little or no motion and be free of motion artifacts such as motion trails, motion blur, jittering or wobbling in areas where there is motion.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.